The present disclosure relates generally to the field of vehicle transmissions. The disclosure more specifically relates to the control of the power path through a transmission to provide multiple speeds in the transmission.
It would be desirable to provide an improved multi-speed vehicle transmission which provides more than one speed using a planetary gear drive arrangement. However, the problems posed by this type of arrangement are particularly complicated because they exist within the complexity of an overall vehicle system. For example, the inputs and outputs of a vehicle transmission experience the torque, speed and power oscillations caused by vehicle dynamics, varying suspension systems, road conditions, loading conditions, engine and motor torque and speed characteristics, operator control, etc. Accordingly, the selection of a solution may result in unforeseen shifting control complications, shifting linkage complications, cost increases, manufacturing efficiency losses, expensive part configurations, performance and control losses, etc. Further complicating the use of this type of transmission is the need to use such transmissions in hybrid vehicles which utilize electric motors for all or portions of the vehicle drive power.